This invention relates to novel polymers and to a process for the preparation thereof. These polymers are polyamides which contain phosphorus atoms as part of the main polymer chain.
This invention also relates to shaped articles, such as films and filaments, formed from these polymers.
The simplest polyamides are those obtained by the self-condensation of lactams, e.g. nylon-6 obtained from caprolactam, and those obtained by condensing a diamine with a dicarboxylic acid or acid derivative, e.g. poly(hexamethylene adipamide) or nylon-66. Whilst simple polymers of this type have many advantages of strength and resistance to harmful and degradative influences of many types, they also have many shortcomings, and even disadvantages, and continual effort has been expended both on improving the properties the polyamides intrinsically possess, and on imparting properties which the simple polyamides do not possess.
For instance, polyamides can be synthesized from mixtures of amines or acids, or substitution reactions can be carried out on previously prepared polyamides, whereby desired substituent groups can be appended to the polyamide chains, so as to provide the polyamides with desired properties. For instance, groups can be added which enable dyestuffs to bind tightly to polyamide chains.
An article by Bello et al. in Macromolecules Vol. 3, pages 98- 100 (1970) describes the preparation of polymers having repeating units of the formulae ##STR1## by the reaction of phosphoric dimethylamido bispiperazide ##STR2## with, respectively, piperazine-1,4-dicarbonyl chloride and oxalyl dichloride.
The object of the present invention is the synthesis of novel phosphorus- and nitrogen-containing polymers. A further object of this invention is the synthesis of polymers which are inherently flame-resistant or non-flammable.